The research will address an environmentally important issue, namely the economy and the preservation of resources and the reduction of waste. Given the energy context, the renovation of the old and energy consuming existing building stock appears essential. But the energy retrofit process also generates waste and consumes a certain amount of raw materials. We could say that the issue of reducing the energy consumption of buildings is now well integrated by architects. That same awareness has not yet been applied to resources and waste issues. Moreover, the lack of data concerning the renovation and construction impacts on material stocks and flows represents an obstacle to achieve a closed loop system in which waste is considered as a resource. This research will investigate these issues by studying some energy retrofit interventions in terms of material impacts also referred to as material balances. As wall as recovery potential, also referred to as recoverability. In practice, the study will first identify and quantify the material and waste consumed and generated by the operation (by weight and volume). Secondly it will propose a qualitative assessment to evaluate the recovery potential of as-built and improved walls in order to integrate a reflection on resources possibilities the as-built environment could represent